The role of neural cell adhesion molecule (NCAM) in the development and maturation of the neuromuscular junction (NMJ) was explored by characterizing structurally and functionally NMJs from postnatal day 11 (P11) to P30 +/+, +/-, and -/- NCAM null mutant mice. Differences in NCAM levels resulted in alterations in the size and shape of NMJs, with -/- NMJs being smaller. Additionally both the wit...

The monovalent thallous ion (Tl) was evaluated at the frog end plate in vitro with intracellular microelectrodes. Recordings included end plate potentials (EPPs), and miniature end plate potentials (MEPPs). Replacement of extracellular potassium (K) by 2.5 mM Tl (a) caused increases in MEPP and EPP amplitudes, MEPP frequency, and quantal content, and (b) caused complete recovery of the EPP faci...

End plates serve as the interface between rigid vertebral bodies and pliant intervertebral disks. Because the lumbar spine carries significant forces and disks don't have a dedicated blood supply, end plates must balance conflicting requirements of being strong to prevent vertebral fracture and porous to facilitate transport between disk cells and vertebral capillaries. Consequently, end plates...

In infant rats adenosine A(2A) receptor-mediated modulation of neuromuscular transmission predominates over A1 receptor-mediated neuromodulation. We investigated whether aging affects this A(2A)/A(1) receptor balance. Evoked (EPPs) and miniature end plate potentials (MEPPs) were recorded from single fibers of (weeks-old) infant (3-4), young adult (12-16), older (36-38), and aged (80-90) male ra...

The effect of Ruthenium Red on synaptic transmission was examined at isolated junctions of the frog, by conventional methods for stimulation and intracellular recording. Ruthenium Red (2.5-10.0 muM) reduces the synaptic potential to subthreshold levels. An analysis of this phenomenon shows that the main action of Ruthenium Red is on the presynaptic nerve terminal where it decreases the number o...

The aqueous extract of the venom glands of black widow spiders was fractionated on a column of Sephadex G-200 and then on a column of DEAE-Sephadex A-50 pH 8.2. A protein fraction was obtained that caused a great increase in the frequency of occurrence of miniature end plate potentials at the frog neuromuscular junction, and caused swelling of the nerve terminals and depleted them of their vesi...

We investigated the relationship between intraterminal Ca(2+) concentration ([Ca(2+)](i)) and the frequency of miniature end plate potentials (MEPPs) at the frog neuromuscular junction by use of ratiometric imaging of fura-2-loaded nerve terminals and intracellular recording of MEPPs. Elevation of extracellular [KCl] over the range of 2-20 mM resulted in increases in [Ca(2+)](i) and MEPP freque...

The end plate mounted at the mouth of the shock tube is a versatile and effective implement to control and mitigate the end effects. We have performed a series of measurements of incident shock wave velocities and overpressures followed by quantification of impulse values (integral of pressure in time domain) for four different end plate configurations (0.625, 2, 4 inches, and an open end). Sho...